The present invention relates to a continuously variable traction roller transmission.
Various kinds of continuously variable traction roller transmissions have been proposed up to the present. One of such continuously variable traction roller transmissions is disclosed, for example, in JP-U 62-128262, or JP-U 63-92859. This transmission includes a member integrated with a valve body which has a piston bore for receiving a piston of a hydraulic cylinder apparatus. Specifically, the valve body, which has a spool bore for receiving a plurality of spools, has also the piston bore.
With such known continuously variable traction roller transmissions, however, the valve body receiving a piston undergoes a great force due to reaction of hydraulic pressure operating on the piston. When undergoing a great force, the valve body will be deformed elastically, causing also deformation of the spool bore for receiving a plurality of spools. This results in obstruction of smooth operation of the spool(s), assuming a situation susceptible of occurrence of so-called valve sticking.